Background: Polycomb group (PcG) proteins influence the development and progression of cancer. However, the mechanism that contributes to tumorigenesis have not been fully understood in head and neck squamous cell carcinoma (HNSCC). Methods: The expression of chromobox 8 (CBX8), a member of the polycomb group (PcG) of proteins, on OSCC patients was determine by quantitative real-time PCR (qRT-PCR) and immunohistochemistry. Specific targeting by miRNAs was determined by software prediction, luciferase reporter assay, and correlation with target protein expression. The functions of miR-410-3p and CBX8 were accessed by transwell migration and invasion analyses using gain- and loss-of-function approaches. Results: Here we found that CBX8 is upregulated in HNSCC tissues and cell lines. Using CBX8 knockdown cDNA microarray, we identify a CBX8-mediated target gene MIPOL1 which is inversely correlated with CBX8 expression in HNSCC tissues. Ectopic expression of MIPOL1 could inhibit tumor invasion and migration, whereas MIPOL1 silencing suppressed these effects in CBX8-knockdown HNSCC cells. Otherwise, depletion of CBX8 also induced p53 activity and increased the expression level of p21 and p27 through MIPOL1-independent manner, which result in cell cycle arrest in G2M phase. Silencing of p53 could inhibit p21 and p27 accumulation in CBX8 knockdown cells. Furthermore, we demonstrated that down-regulation of miR-410-3p promoted HNSCC cells migration and invasion through directly targeting CBX8. Overexpression of miR-410-3p decreased CBX8 expression and reduced migration and invasion, while ectopic expression of CBX8 rescued the miR-410-3p-reduced migration and invasion. In clinical samples, miR-410-3p level closely inversely correlated with CBX8 and positively correlated with MIPOL1. Conclusions: Collectively, our findings indicate that miR-410-3p may act as a tumor suppressor via negatively regulating CBX8. The newly identified miR-410-3p/CBX8/MIPOL1 and miR-410-3p/CBX8/p53 signaling axes may suggest new therapeutic strategies against HNSCC.
Date:
2019-05
Relation:
Journal of Clinical Oncology. 2019 May;37(15, Suppl. S):Abstract number e17534.
